Chemical kinetics
Chemical kinetics is study of the rates of chemical processes. The law of mass action states that the speed of chemical reaction is proportional to the quantity of the reacting substances. Chemical kinetics deals with the experimental determination of reaction rates from which rate laws and rate constants are derived. Comparatively simple rate laws exist for zero-order reactions, 1st-order reactions, and 2nd-order reactions, and can be derived for others. In the consecutive reactions the rate-determining step determines the kinetics. The detailed explanation at molecular level how a reaction proceeds is known as reaction mechanism. The steady-state approximations are a technique for obtaining a rate law from proposed mechanism. A number of factors influence rates of chemical reactions, and these are summarized as follows;
Nature of Reactants
- Temperature
- Concentration Effect
- Heterogeneous reactions
- Catalysts
The Arrhenius equation provides the dependence of the rate constant k of the chemical reactions on temperature T and activation energy Ea, where A is pre-exponential factor or simply the prefactor and R is gas constant.
Another Arrhenius-like expression appears in "transition state theory" of chemical reactions here ΔG‡ is the Gibbs free energy of activation, kB is Boltzmann's constant, and h is the Planck's constant.
Few applications are, the mathematical models which describe chemical reaction kinetics provide chemists and chemical engineers with the tools to better understand and describe the chemical processes such as microorganism growth, stratospheric ozone decomposition, food decomposition, and the complex chemistry of biological systems. These models can be used in the design or modification of chemical reactors to optimize product yield, efficiently separate products, and remove environmentally harmful by-products. While performing catalytic cracking of heavy hydrocarbons into the gasoline and light gas, for instance, kinetic models can be used to find temperature and pressure at which the highest yield of heavy hydrocarbons into gasoline will take place.